Photographic elements having layers comprising filter dyes are known. These filter dyes may be used for a variety of purposes, such as absorber dyes in photographic emulsion layers to improve the image sharpness of that layer, general purpose filter dyes for absorbing light of a particular wavelength so it does not expose or exposes at a reduced intensity a lower layer in the element, or as antihalation dyes to reduce halation in the image-forming layers.
Filter dyes may be present in essentially layer of a photographic element where it is desired to absorb radiation in the region of the spectrum where the dye absorbs light, such as an interlayer, a radiation-sensitive layer, an overcoat layer, an undercoat layer, a backing layer, or others known in the art. Absorber dyes (also called intergrain absorber dyes) are generally present in the radiation-senstive layers of photographic elements. Antihalation layers may be located on either side of a transparent support carrying radiation sensitive layers, particularly silver halide emulsion layers. Moreover, such antihalation layers may be coated between two or more silver halide emulsions layers in a multilayer element or as a backing layer on the side of the support away from the light sensitive layers.
The development of information recording equipment using semiconductor laser diodes emitting in the infrared spectral region has required a parallel development of photographic elements, particularly silver halide photographic elements, with appropriate spectral sensitivity. Such elements often require the presence of filter dyes that absorb infrared radiation in one or more layers of the element, for example, as antihalation dyes or absorber dyes.
Such filter dyes should:
(1) filter light in the region from about 730 nm to about 900 nm, depending on the emission wavelength of the laser diode (a common laser emission wavelength is about 800 nm and other typical laser emission wavelengths are about 750, 780, 820, and 870 nm),
(2) be water soluble at levels of at least 5 mg/ml so as to allow aqueous dissolution of the dye and provide compatibility with hydrophilic layers, and
(3) leave little or no stain in the processed film.
U.S. Pat. No. 4,362,800 discloses 1,1,1'1'-tetramethyl-3,3'-bis(sulfoalkyl)-1H-benz[e]indolotricarbocyanine sodium salt. This dye has been used with some success as a photographic filter dye, but it tends to leave a greenish stain after processing. Such a stain is objectionable. Thus, a nonstaining infrared filter dye is needed.